FREQUENTLY ASKED QUESTIONS
Principles of Operation
Q: Is the thermal resistance of the air gap region large enough to be a problem?
A: No—For example, in our current prototype device the thermal resistance of the air gap region is 0.02 °C/W.
Q: How does a hydrodynamic air bearing work?
A: A video of a very rudimentary hydrodynamic air bearing is available at
Rayleigh Hydrodynamic Thrust Bearing - YouTube
Q: Does the stationary base plate simply consist of a solid piece of thermally conductive material?
A: As in a conventional forced-convection heat sink, the base plate acts as a heat spreader, and may comprise solid piece of thermally
conductive material or be implemented in the form of a heat pipe.
Q: Is the radial-air-flow architecture depicted here the only possible device geometry?
A: No—a wide variety of device geometries are possible, including axial-flow configurations, and devices in which more than one rotating
cooling fin/impeller operate in parallel to further lower thermal resistance.
Real-World Practicality
Q: Can the device be mounted in any orientation?
A: Yes—the air bearing assembly is held together by magnetic attraction (between the stator and permanent-magnet rotor).
Q: Is a an air bearing suspension mechanically stiff and rugged?
A: Yes—because the rate of change of the pressure lifting force with respect to gap distance is extremely large.
Q: What other types of equipment use air bearings?
A: Devices range from hard disk read–write heads to large CNC milling machine spindles.
Q: What if small (less than 0.001″) particulates are somehow introduced into the air gap region?
A: They are swept outward and ejected by centrifugal force.
Q: How do you prevent contact between the air bearing surfaces at low rpm?
A: Depending on the application, one of several simple, passive mechanisms may be implemented.
Manufacturability
Q: Does the 0.001″ air gap require tight manufacturing tolerances?
A: No—the hydrodynamic air bearing gap distance is passively self-regulating.
Q: Is the surface quality/flatness spec of a conventional heat sink mating surface adequate?
A: Yes—For example, conventional fabrication processes such as cold forging can be used.
Performance
Q: Based on laboratory testing of early prototype devices, what level of performance is expected for a CPU cooler based on
Sandia’s air bearing heat exchanger principle?
A: We expect to achieve 0.05 °C/W in package that is considerably smaller and quieter than conventional high-performance CPU coolers.
Because low-thermal-resistance CPU coolers are particularly susceptible to performance degradation due to cooling-fin fouling (a thin
layer of dust can easily increase thermal resistance by a factor of 2), the added benefit of immunity to fouling is also a crucial performance
specification. Further reductions in thermal resistance would likely involve engineering trade-offs against device size and dBa rating.
Zurück zum Artikel: Sandia-Kühler: Rotierender Lüfter fertig für die Lizenzierung - Video zeigt Lüfter im Einsatz
), was mit lärm und abnutzung einhergeht, oder es ist eine flüssigkeit o.ä. dazwischen, dann ists zwar ruhiger, aber es findet keine vernünftige wärmeübertragung zwischen chip und kühler statt (wobei der herr sich mich 150 watt ja keine einfache region zum wildern ausgesucht hat)
